MUMBAI (Thomson Reuters Foundation) - Nearly 200 child workers, some as young as eight, were rescued from bangle factories in Hyderabad in southern India over the last week, as part of a crackdown that will continue until the end of the month, police said on Tuesday.

Most children rescued were aged between 8 and 14 and came from the poor northeastern states of Bihar, West Bengal and Assam, said officials who are part of "Operation Smile", a national movement to tackle child labor and missing children.

"We are investigating the nexus between the employers and the traffickers," said Swathi Lakra, additional commissioner of police in Hyderabad, who is monitoring the rescue operations.

"In many cases, parents are only too willing to send their children for work, which works well for the traffickers."

Earlier this month, around 200 children, most of them aged under 14, were freed from a brick kiln about 40 km (25 miles) from Hyderabad, capital of Telangana state.

Activists said the southern states of Telangana and Andhra Pradesh had become hubs for child labor and child trafficking.

But the rescues, carried out as month-long special drives by the police and child rights charities twice a year, have brought the numbers down.

"Over 2,000 children have been rescued from Hyderabad alone since 2015 and the numbers in each drive have gradually been declining," Mohammed Imtiaz Raheem, Hyderabad district's child protection officer, told the Thomson Reuters Foundation.

In 2015, the International Labour Organization (ILO) put the number of Indian child workers aged between five and 17 at 5.7 million, out of 168 million globally.

More than half work in agriculture and over a quarter work in the manufacturing sector, the ILO said.

In Hyderabad, the bangle factories prefer to use children for their nimble fingers and sharp eyes as they deftly stick small glittering stones on bangles made of lac that are popular with tourists around the historical monument of Charminar.

"Most of the children rescued were from the Old City where most bangle factories are located. We also found children working in furniture shops and hotels," Lakra said.

The rescued children are currently staying at a shelter home and will be sent back to their families in their homes states.

Last year, more than 200 children aged 6 to 14 were rescued from the bangle factories of Hyderabad. Local media reported that children complained of respiratory illnesses as they worked long hours in a small windowless room.